Avoiding failure of an initial program load in a logical partition  of a data storage system

ABSTRACT

An initial program load (IPL) of a logical partition (LPAR) is managed by establishing a logical path to the LPAR from a storage controller. When a notice is received by the storage controller from the LPAR that the IPL has commenced, the LPAR address is stored in a data structure. After the storage controller initiates a pack change state interrupt, the stored address is compared with the addresses in a list of all LPARS to which the interrupt is directed. If the list of addresses includes the stored address, the stored address is removed from the list. Thus, the pack change state interrupt is transmitted only to the addresses in the list, leaving the LPAR to complete the IPL without interruption. After the storage controller receives a notice from the LPAR that the IPL has completed, the address of the LPAR is removed from the data structure.

TECHNICAL FIELD

The present invention relates generally to data storage systems and, inparticular, to initial program load operations in a logical partition ofa data storage system.

BACKGROUND ART

A data storage system typically includes one or more storage controllerscoupled one or more data storage devices, such as hard disk drives(HDDs). The controller receives read and write requests from one or morehosts, processes the requests and, in response reads the requested datafrom or writes (records) data to the storage device. Larger storagesystems enable one physical host to be divided into one or more logicalpartitions (LPARs) which operate as separate, virtual computers. TheLPARs may also run under different operating systems and may executedifferent application programs. During the initial program load (IPL) ofthe LPAR, logical paths are established between the host and the storagecontroller, enabling the two to communicate with each other. Worldwidenetwork node numbers (WWNN) are used to enable links between thecommunicating devices.

During the IPL of one LPAR, another LPAR may decide to change the stateof peer-to-peer remote copy (PPRC) devices, such as from ‘PPRC FullDuplex’ to ‘PPRC Suspended,’ using a ‘Freeze’ command from the host tothe storage controller.

When the ‘Freeze’ command is executed, the storage controller sends apack change or state change interrupt for all devices in a PPRCrelationship and to all known paths and path groups. The interrupt maybe received by an LPAR which is undergoing an IPL. Should this occur,the LPAR is forced to disrupt the IPL and contend with the pack changeinterrupt and the ensuing validation and query commands. Because thepack change interrupt is sent one per path for each device that changedstate from ‘PPRC Full Duplex’ to ‘PPRC Suspended,’ the large number ofpack changes and required command processing can cause the IPL of theLPAR to take a very long time to complete. In some cases, the IPL mayfail.

SUMMARY OF THE INVENTION

The present invention reduces the performance impact on an LPAR IPL andreduces the risk of IPL failure due to contending with pack change orstate change interrupts received during an IPL. An initial program load(IPL) of a logical partition (LPAR) is managed by establishing a logicalpath to the LPAR from a storage controller. When a notice is received bythe storage controller from the LPAR that the IPL has commenced, theaddress of the LPAR is stored in a data structure. Subsequently, afterthe storage controller initiates a pack change state interrupt, thestored address is compared with the addresses in a list of all LPARs towhich the pack change state interrupt is directed. If the list ofaddresses includes the stored address, the stored address is removedfrom the list. Thus, the pack change state interrupt is transmitted onlyto the addresses in the list, leaving the LPAR to complete the IPLwithout interruption. After the storage controller receives a noticefrom the LPAR that the IPL has completed, the address of the LPAR isremoved from the data structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a data processing system in which thepresent invention may be implemented;

FIG. 2 is a flowchart of one aspect of a method of the presentinvention; and

FIGS. 3, 4, 5 are a flowcharts of further aspects of a method of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a block diagram of a data processing system 100 in which thepresent invention may be implemented. The system 100 includes one ormore hosts, collectively represented by a host 110, one or more storagecontrollers, collectively represented by a storage controller 120, andone or more storage devices, collectively represented by the storagedevice 140. The storage device 140 may be any type of storage device,such as hard disk drives, or a combination of devices. The host 110includes a memory 112 for storing computer-readable code containingprogram instructions and a processor 114 which executes the instructionsstored in the memory 112. The host 110 can create multiple logicalpartitions (LPARs), two of which are illustrated in FIG. 1 as 116 a and116 b. Each LPAR 116 a, 116 b is capable of running one or moreapplications 118 a, 118 b, respectively.

The storage controller 120 includes a memory 122 for storingcomputer-readable code containing program instructions and a processor124 which executes the instructions stored in the memory 122. Thestorage controller also includes host adapters or interfaces,represented by a host adapter 126, through which communications with thehost 110 pass, and device adapters or interfaces, represented by adevice adapter 128, through which communications with the storage device140 pass. The storage controller 120 further includes two datastructures 130, 132. Either or both of the data structures 130, 132 maybe stored in the memory 122 or may be stored in other memory.

A method of the present invention will now be described with referenceto the flowcharts of FIGS. 2-5. The method may be executed by theprocessors 114, 124 from program instructions stored in the memorydevices 112, 122, may performed by hardware, such as ASICs in the host110 and storage controller 120, or by any combination. An LPAR 116 abegins an initial program load (step 200) and establishes acommunications path with the storage controller 120 (step 202). The LPAR116 a then transmits a command to the storage controller 120 (step 204)notifying the storage controller 120 that an IPL is underway. Thecommand may be a single command having two states, such as an IPLindicator with “set” and “reset” states. Alternatively, the command maybe one of two separate commands, the second having an “IPL Complete”indicator as described below. The command, whether a single command orone of two commands, can be part of new orders of the existing definedsystem operation (DSO) command or new z/Os command(s) that are allowedthrough most exception conditions, such as “Reserve”, “Long Busy,” etc.

Turning now to FIG. 3 (step 206), the storage controller 120 receivesthe command from the LPAR 116 a (step 300) and stores the address orother identity of the LPAR 116 a in a data structure 130 (step 302).Preferably, the data structure 130 is sufficiently large to store theaddresses of more than one LPAR which are undergoing an IPL. Alsopreferably, the address of the LPAR comprises the worldwide network nodenumber (WWNN) of the LPAR 116a. By contrast, a worldwide port number(WWPN) only identifies a host adapter port which is not sufficientlyspecific of the present invention. The data structure 130 may be aregister, a location in the memory 122, a lookup table or any otherstructure associated with the storage controller 120 capable of storingthe identity of the LPAR 116 a.

When the storage controller 120 initiates a pack change state interrupt(FIG. 4, step 404), it generates a list of the addresses, such as theWWNNs, of all devices in a PPRC relationship and to all known paths andpath groups (step 406). The list may be stored in a second datastructure 132. As with the first data structure 130, the second datastructure 132 may be a register, a location in the memory 122, a lookuptable or any other structure associated with the storage controller 120capable of storing the addresses of recipients of the pack change stateinterrupt. Instead of then queuing the addresses, the storage controller120 first compares any address(s) in the first data structureidentifying LPARs which are undergoing an IPL (step 408). If the addressof the LPAR 116 a is found in the data structure list 132, the addressis removed from the list (step 410). Next, or if the address of the LPAR116 a is not found in the list 132, the storage controller 120 queuesthe addresses remaining in the 132 list and sends the pack change stateinterrupt to only those addresses (step 412). Thus, the LPAR 116 a andany other LPAR undergoing an IPL will not have to contend with such aninterrupt.

When the IPL of the LPAR 116 a is completed (step 208, FIG. 2), the LPAR116 a sends a command to the storage controller (step 210) indicatingthat the IPL is complete. Moving to FIG. 5 (step 212), the storagecontroller 120 receives the command (step 514). As described above, thecommand be the second state of the original command or may be a separatecommand. When the storage controller 120 has received the second commandfrom the LPAR 116a, it removes the address of the LPAR 116 a from thefirst data structure 130 (step 516), allowing the LPAR 116a to receivesubsequent pack change state interrupts.

It is important to note that while the present invention has beendescribed in the context of a fully functioning data processing system,those of ordinary skill in the art will appreciate that the processes ofthe present invention are capable of being distributed in the form of acomputer readable medium of instructions and a variety of forms and thatthe present invention applies regardless of the particular type ofsignal bearing media actually used to carry out the distribution.Examples of computer readable media include recordable-type media suchas a floppy disk, a hard disk drive, a RAM, and CD-ROMs andtransmission-type media such as digital and analog communication links.

The description of the present invention has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain theprinciples of the invention, the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated. Moreover, although described above withrespect to methods and systems, the need in the art may also be met witha computer program product containing instructions for managing aninitial program load (IPL) of a logical partition (LPAR) established ina host or a method for deploying computing infrastructure comprisingintegrating computer readable code into a computing system for managingan initial program load (IPL) of a logical partition (LPAR) establishedin a host.

1. A method for managing an initial program load (IPL) of a logicalpartition (LPAR) established in a host, the method comprising:establishing a logical path to an LPAR; receiving a first notice fromthe LPAR that an IPL of the LPAR has commenced; storing the address ofthe LPAR in a data structure indicating active IPL processing;initiating a pack change state interrupt; comparing the stored addresswith the addresses in a list of all LPARs to which the pack change stateinterrupt is directed; if the list of addresses includes the storedaddress, removing the stored address from the list; transmitting thepack change state interrupt to only the addresses in the list; receivinga second notice from the LPAR that the IPL of the LPAR has completed;and removing the address of the LPAR from the data structure.
 2. Themethod of claim 1, further comprising, prior to transmitting the packchange state interrupt to the addresses in the list, placing only theaddresses in the list in a queue.
 3. The method of claim 1, wherein thefirst and second notices from the LPAR comprise a single command with anIPL indicator, the IPL indicator having first and second states.
 4. Themethod of claim 3, wherein the single command comprises a definedsubsystem operation command.
 5. The method of claim 1, wherein the firstnotice from the LPAR comprises a first command and the second noticefrom the LPAR comprises a second command.
 6. The method of claim 5,wherein the first and second commands each comprise a defined subsystemoperation command.
 7. A method for managing an initial program load(IPL) of a logical partition (LPAR) established in a host, the methodcomprising: commencing an IPL of an LPAR, the LPAR having a worldwidenetwork node number (WWNN); establishing a logical path to a storagecontroller; transmitting a first notice, including the WVVNN, to thestorage controller of the IPL, whereby the storage controller stores theWWNN of the LPAR and whereby further the storage controller does notsend a pack change interrupt to the LPAR; and transmitting a secondnotice, including the WWNN, to the storage controller of the completionof the IPL, whereby the storage controller deletes the WWNN of the LPARfrom its storage.
 8. The method of claim 7, wherein the first and secondnotices from the LPAR comprise a single command with an IPL indicator,the IPL indicator having first and second states.
 9. The method of claim7, wherein the first notice from the LPAR comprises a first command andthe second notice from the LPAR comprises a second command.
 10. A methodfor deploying computing infrastructure, comprising integrating computerreadable code into a computing system, wherein the code, in combinationwith the computing system, is capable of performing the following:receiving a first notice from the LPAR that an IPL of the LPAR hascommenced; storing the address of the LPAR in a data structureindicating active IPL processing; initiating a pack change stateinterrupt; comparing the stored address with the addresses in a list ofall LPARS to which the pack change state interrupt is directed; if thelist of addresses includes the stored address, removing the storedaddress from the list; transmitting the pack change state interrupt toonly the addresses in the list; receiving a second notice from the LPARthat the IPL of the LPAR has completed; and removing the address of theLPAR from the data structure.
 11. The method of claim 10, whereinstoring the address in the data structure comprises storing a worldwidenetwork node number of the LPAR in the data structure.
 12. The method ofclaim 10, wherein the first and second notices from the LPAR comprise asingle command with an IPL indicator, the IPL indicator having first andsecond states.
 13. The method of claim 12, wherein the single commandcomprises a defined subsystem operation command.
 14. The method of claim10, wherein the first notice from the LPAR comprises a first command andthe second notice from the LPAR comprises a second command.
 15. Themethod of claim 14, wherein the first and second commands each comprisea defined subsystem operation command.